http://www.fueleconomy.gov/feg/sbs.htm
Compare your 135 and your desired M3. This site will give you an apples-to-apples comparison. All the other evidence given here in this thread is anecdotal. Granted the site is in U.S. dollars, but you can at least see the differences.
Comparing a 2008 MT 135 coupe and a 2011 MT M3 coupe, the M3's annual fuel cost is $740 higher.